Date: Thu, 28 Jul 2005 14:13:49 +0200 From: des@des.no (=?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?=) To: ray@redshift.com Cc: freebsd-amd64@freebsd.org Subject: Re: Benchmarks: AMD64 vs i386 on Dual 246 Opteron Message-ID: <86mzo7yvpe.fsf@xps.des.no> In-Reply-To: <3.0.1.32.20050728013152.00a4d188@pop.redshift.com> (ray@redshift.com's message of "Thu, 28 Jul 2005 01:31:52 -0700") References: <3.0.1.32.20050728013152.00a4d188@pop.redshift.com>
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ray@redshift.com writes: > While this sounded like a long shot, I loaded FreeBSD 5.4 i386 on > the machine and after applying the exact same configuration to the > OS, Apache, PHP and MySQL, re-ran the benchmarks. Much to my > surprise, just changing the OS from 64 bit to 32 bit caused the > machine to double in speed. The results are attached in an Excel > spreadsheet. So the exact same machine, running the identical > configuration, performed roughly twice as fast when running FreeBSD > 5.4 i386 vs FreeBSD 5.4 AMD64. Something about this seems so wrong > to me :-) 64-bit code uses up to twice as much CPU cache and twice as many memory accesses to do the same work as the equivalent 32-bit code. DES --=20 Dag-Erling Sm=F8rgrav - des@des.no
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